On-line fluid sensor

ABSTRACT

A touch sensor is associated with a housing that is adapted for attachment to the outer perimeter of a fluid conduit. The housing can be attached to the fluid conduit such that the touch sensor can detect the presence of fluid within the fluid conduit. The output of the touch sensor can be used by an indicator or processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and incorporates by reference thedisclosure of U.S. Provisional Patent Application No. 60/797,450, filedon May 4, 2006.

BACKGROUND OF THE INVENTION

This present invention is directed to a fluid sensor for detecting fluidinside a tube or other fluid conduit, for example, a pipe or hose. Moreparticularly, the present invention is directed to a fluid sensor thatcan be mounted on or to the outer surface of a fluid conduit withoutpenetrating its pressure barrier.

Fluid sensors are known in the art. Conventional fluid sensors, however,typically are installed within or in line with a fluid conduit. As such,conventional fluid sensors typically interact with the fluid they areintended to detect. This interaction can be undesirable for severalreasons. For one, this interaction can substantially disturb the flow ofthe fluid through the fluid conduit. For another, the sensor can bedamaged by exposure to the fluid, particularly in applications where thefluid is corrosive or applications involving high flow rates orturbulent flow. Further, such “in-line” applications typically requirebreaching the pressure barrier in order to install the sensor and/orrelated hardware and accessories. As such, conventional sensorstypically cannot be installed while the fluid conduit is “on line” or inuse. Moreover, any penetrations in the pressure barrier that may berequired for installation and/or operation of a conventional fluidsensor can compromise the structural integrity of the fluid conduit andintroduce additional potential leak paths.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a fluid sensor according to the presentinvention partially installed to a tube;

FIG. 2 is a perspective view of a fluid sensor according to the presentinvention partially installed to a tube; and

FIG. 3 is a perspective view of a fluid sensor according to the presentinvention installed to a tube.

DETAILED DESCRIPTION OF THE DRAWINGS

A preferred embodiment of a fluid sensor 10 according to the presentinvention includes a touch sensor 12 associated with a housing 14 thatis adapted for installation to the outside of a fluid conduit 16, forexample, a pipe, tube, or hose, made of non-conductive material, forexample, plastic or rubber. Fluid sensor 10 is especially well-suitedfor use in connection with rubber and other flexible tubes and hosesbecause the nature of such flexible tubes and hoses allows for closeconformance of fluid sensor 10 to such tubes or hoses and elimination orminimization of air gaps between such tubes and hoses and fluid sensor10, as discussed further below. Fluid conduit 16 is illustrated in thedrawings as being substantially cylindrical. Fluid sensor 10, however,can be adapted for use with non-cylindrical conduits and open channels,as well, as would be understood by one skilled in the art.

Housing 14 is illustrated as a molded plastic clam shell having twoportions 14A,14B joined by a living hinge 24. The interior surfaces ofhousing portions 14A,14B are adapted for close conformance to the outersurface of fluid conduit 16 when installed thereto, as would beunderstood by one skilled in the art. Because the presence of air gapsbetween the inner surface of housing 14 and the outer surface of fluidconduit 16 can adversely affect the performance of fluid sensor 10,housing 14 preferably is adapted for installation to fluid conduit 16 ina manner that eliminates or minimizes air gaps between the inner surfaceof housing 14 and the outer surface of fluid conduit 16. Housing 14preferably includes a positive lock latching mechanism, for example, amolded-in snap-lock assembly feature, such as snap-lock assembly 28, forsecuring housing 14 to fluid conduit 16, as would be understood by oneskilled in the art. In alternate embodiments, housing 14 can take otherforms and be made of different materials and/or by different processes.For example, housing 14 can be formed as two distinct pieces made of anysuitable material that are later joined using one or more ofsnap-assembly features, a hinge mechanism, a tongue and groove or taband slot arrangement, hose clamps, or other means, as would beunderstood by one skilled in the art. Also, housing 14 can be formed astwo distinct pieces including one or more flanges to facilitate assemblyusing clips, screws, or other fasteners.

Touch sensor 12 is associated with the inner surface of housing 14 suchthat touch sensor 12 can detect the presence of fluid within fluidconduit 16. Preferably, touch sensor 12 is molded into housing 14 usinginjection molding, overmolding, or other molding techniques. U.S. Pat.No. 6,897,390, the disclosure of which is incorporated herein byreference, illustrates certain molding techniques that could be used topractice the present invention. Alternatively, touch sensor 12 could bemounted on an inner or outer surface of housing 14. In such embodiments,touch sensor 12 could be mounted directly on such inner or outer surfaceor it could be fabricated on a separate, preferably flexible, substratewhich in turn would be mounted on an inner or outer surface of housing14. Molding touch sensor 12 into housing 14, however, is preferred oversurface mounting touch sensor 12 because a molded-in touch sensor isless susceptible to damage, particularly during and after installationof fluid sensor to fluid conduit 16.

Touch sensor 12 preferably is a field effect touch sensor provided byTouchSensor Technologies of Wheaton, Ill. and/or as disclosed in one ormore of U.S. Pat. Nos. 5,594,222, 6,310,611, and 6,320,282 and UnitedStates Publication No. 2003/0122432 A1, the disclosures of which areincorporated herein by reference. Other types of sensors may be usedwith the present invention, as well.

Preferably, touch sensor 12 includes a first sensing electrode 18 havinga closed geometric form and a second sensing electrode 20 in the form ofa narrow electrode that substantially surrounds first sensing electrode18. (FIG. 1 illustrates second sensing electrode 20; first sensingelectrode 18 is “behind” second sensing electrode 20.) Alternatively,first sensing electrode 18 and second sensing electrode 20 can haveother shapes and spatial relationships as would be understood by oneskilled in the art. In some embodiments, second sensing electrode 20 canbe omitted. Preferably, touch sensor 12 also includes an integratedcontrol circuit 22 located in close proximity to first sensing electrode18 and (when used) second sensing electrode 20. Integrated controlcircuit 22, when used, preferably is embodied as a TS-100 integratedcircuit chip provided by TouchSensor Technologies, LLC of Wheaton, Ill.The TS-100 chip is an embodiment of the control circuit disclosed inU.S. Pat. No. 6,320,282. In such embodiments, touch sensor 12 preferablyfurther includes first and second resistors R1,R2 coupled, respectively,to first and second sensing electrodes 18,20 and to integral controlcircuit 22.

Fluid sensor 10 also includes power lead P and signal lead S forproviding power to touch sensor 12 and conveying a signal from theoutput of touch sensor 12 to a remote circuit or device, for example, aremote processor, indicator, or display.

With fluid sensor 10 installed to fluid conduit 16, touch sensor 12 candetect the presence or absence of fluid within fluid conduit 16, aswould be understood to one skilled in the art. The output of touchsensor 12 is indicative of the presence or absence of fluid within theportion of fluid conduit 16 proximate touch sensor 12 of fluid sensor16. Plural fluid sensors 10 could be used to determine the flow rate ofa fluid in fluid conduit 16. This could be accomplished by installingtwo or more fluid sensors 10 on fluid conduit 16 at predeterminedspacing. A processor receiving the outputs of the two or more fluidsensors could determine flow rate in fluid conduit 16, particularly atthe time flow is initially established, as a function of the spacingbetween fluid sensors 10, the size of fluid conduit 16, the elapsed timebetween a first such sensor detecting fluid and a second such sensordetecting fluid in fluid conduit 16, and/or any other relevant factors,as would be understood by one skilled in the art.

The embodiments illustrated and described herein are intended to beillustrative and not limiting. One skilled in the art would recognizethat these embodiments could be modified without departing from thescope of the invention, which is defined by the following claims.

The invention claimed is:
 1. A fluid sensor comprising: a housingadapted to substantially surround a fluid conduit in close conformancethereto; and a touch sensor molded into said housing; wherein said touchsensor detects the presence or absence of a fluid within said fluidconduit proximate said sensor; wherein said housing is adapted toconform to said fluid conduit such that substantially no air gap existsbetween said housing and said fluid conduit; and wherein said touchsensor outputs a signal indicative of the presence or absence of saidfluid within said fluid conduit proximate said sensor.
 2. The fluidsensor of claim 1 wherein said housing is adapted for attachment to saidfluid conduit without breaching a pressure barrier of said fluidconduit.
 3. The fluid sensor of claim 2 wherein said fluid conduit issubstantially tubular and said housing is adapted for engagement aboutthe circumference of said fluid conduit.
 4. The fluid sensor of claim 2wherein said housing comprises a first portion, a second portion, and aliving hinge coupling said first portion and said second portion.
 5. Thefluid sensor of claim 4 wherein said housing further comprises apositive lock latching mechanism.
 6. The fluid sensor of claim 4 whereinsaid housing comprises a clam shell housing.
 7. The fluid sensor ofclaim 4 wherein said first portion of said housing includes a firstsection adapted for conforming to said fluid conduit and a secondsection depending from said first section adapted to contain said touchsensor.
 8. The fluid sensor of claim 2 wherein said housing comprises afirst portion, a second portion, and means for coupling said firstportion and said second portion.
 9. The fluid sensor of claim 1 whereinsaid fluid is a liquid.
 10. The fluid sensor of claim 1, said touchsensor comprising a first sensing electrode, a second sensing electrodesubstantially surrounding said first sensing electrode, and an integralcontrol circuit in close proximity to said first and second sensingelectrodes.
 11. The fluid sensor of claim 1 wherein said housing isinjection molded about said touch sensor.
 12. The fluid sensor of claim1 wherein said housing is overmolded about said touch sensor.
 13. Thefluid sensor of claim 1, wherein said touch sensor is encapsulated intosaid housing.